The present invention is generally directed to toner compositions, and more specifically to colored encapsulated toner compositions. In one embodiment, the present invention is related to colored magnetic image character recognition toner compositions that can, for example, be selected for single component, and two component development, and more specifically for a number of imaging and printing processes useful for generating documents which are magnetically recognizable. More specifically, the colored encapsulated toners can be selected to develope images or characters on documents such as personal checks and other security documents which are subsequently processed in reader/sorters which are sensitive to magnetic properties of the printed images. In one embodiment of the present invention, there are provided colored toners for generating documents, such as checks, including for example dividend checks, turn around documents such as invoice statements like those submitted to customers by American Express and VISA, corporate checks, highway tickets, rebate checks, and other documents with magnetic codes thereon. In an embodiment, the present invention relates to toner compositions comprised of a polymer binder, a magnetic metal material comprised of a component with a high magnetic saturation moment of about 85 to about 400 emu per gram, and preferably from about 90 to about 200 emu per gram, a remanence of about 25 to about 300 Gauss, and preferably, from about 30 to about 200 Gauss, a coercivity of about 70 to about 1,600 Oersteds, and preferably from about 80 to about 800 Oersteds, and where the ratio of the magnetic saturation moment in emu per gram to the coercivity in Oersteds is in the range of about 2 to about 1 to 5, and preferably in the range of about 1.5 to 1 to about 1 to 3, and an average particle size of about 0.5 micron to about 6 microns, and preferably from about 0.8 to about 4 microns, a whitening agent, a color pigment, dye or mixture thereof. In one embodiment of the present invention, there are provided colored magnetic encapsulated toner compositions comprised of a core comprised of a polymer binder, a magnetic metal material comprised of a metal such as cobalt and the like of average particle size of 2 microns, a whitening agent, and a color pigment, and wherein the core is encapsulated in a polymeric coating such as a polyurea, a polyurethane, a polyamide, a polyester, or mixtures thereof, and wherein the shell contains on the surface a conductive fine powdered additive comprised of a conductive metal oxide, such as tin oxide doped with bismuth or antimony, to impart to the toner a volume resistivity of about 10,000 ohm-cm to about 1,000,000 ohm-cm suitable for ionographic imaging processes, and wherein image smearing and offsetting of the toner to read and write heads, including offsetting to the protective foil that may be present on the aforesaid heads in magnetic ink character recognition processes and apparatus inclusive of, for example, the read and write heads present in MICR (magnetic ink character recognition) reader/sorters such as the commercially available IBM 3890.TM., NCR 6780.TM., reader/sorters from Burroughs Corporation, and the like is substantially avoided or minimized. Some of the reader/sorter printers contain protective foils thereon, reference for example the IBM 3890.TM., and the problems associated with such protective foils as illustrated herein with respect to read and write heads with no foils are alleviated with the processes of the present invention. Moreover, in another embodiment the present invention related to encapsulated toner, compositions comprised of a core comprised of a low surface-energy organosilane polymer binder to minimize or remove unwanted offsetting properties, a magnetic material comprised of metals such as cobalt, a whitening agent, a color pigment, and a shell polymer which may contain a flexible structural moiety such as a polyether or polymethylene segment to improve its packing, and thus enhance resistance to core component diffusion or leaching through the toner shell structure.
Examples of advantages associated with the encapsulated compositions of the present invention in embodiments thereof include brilliant image color, and wide color variety; use thereof in many inductive single component development systems; cold pressure fixability; high image fix; nonagglomerating and excellent shelf life stability of, for example, up to 2 years in some instances; and suitability for use in magnetic ink characterization recognition technology (MICR), highlight color reprographic processes, especially xerographic and ionographic imaging and printing processes. One specific advantage of the colored toner compositions of this invention is the capability of producing MICR documents for machine readable printing, where the documents can be printed in bright color. A specific example of the advantage of these toners in printing MICR documents is to produce MICR readable characters in any color of choice. In another specific example, using the toner of this invention, an entire document comprised of a color image and a color MICR readable image can be printed in various colors using an electrophotographic imaging device with only a single development step.
The documents, including the personal checks mentioned herein, can be obtained, for example, by generating a latent image thereon and subsequently developing the image, reference U.S. Pat. No. 4,517,268 and U.S. Pat. No. Re. 33,172, the disclosures of which are totally incorporated herein by reference, with the encapsulated colored toner compositions illustrated herein. The developed image that has been created, for example, in the Xerox Corporation 9700.TM. MICR printer, reference the aforesaid '268 patent, can contain thereon, for example, the characters zero, 1,2,3,4,5,6,7,8, and 9, and up to four symbols (E-13B and CMC-7 font), which characters are magnetically readable by the IBM 3890.TM., or other similar apparatus.
In one embodiment, the present invention is directed to MICR processes wherein there are selected encapsulated colored toner compositions comprised of a core comprised of a polymer resin, a cobalt magnetic pigment of high magnetic saturation and remanance, colored pigment, dye and mixture thereof, and a polymeric shell such as a polyurea, polyurethane, polyamide, polyester, or mixtures thereof.
The colored toner compositions of the present invention can, in one specific embodiment, be prepared by first dispersing the toner precursor component materials into stabilized microdroplets of controlled droplet size and size distribution, followed by shell formation around the microdroplets via interfacial polymerization, and subsequently generating the core polymer resin by addition polymerization, preferably free radical polymerization, within the newly formed microcapsules. Thus, in one embodiment, the present invention is directed to a process for the preparation of encapsulated colored MICR toner compositions, which process comprises (1) dispersing a mixture of an oil-soluble shell monomer, an addition monomer or plurality of monomers up to, for example, 25, a suitably functionalized organosilane capable of undergoing copolymerization with the core monomer, and free radical initiator(s), a magnetic pigment, whitening agent, and colorants into microdroplets in an aqueous solution of certain surfactants such as poly(vinyl alcohol) and the like; (2) subjecting the microdroplet dispersion to an interfacial polycondensation reaction by adding a water-soluble shell monomer component(s); and (3) subsequently affecting the core resin-forming addition polymerization by heating, reference for example U.S. Pat. No. 5,013,630 and U.S. Pat. No. 5,023,159, the disclosures of which are totally incorporated herein by reference.
In a patentability search report, the following United States patents are listed: U.S. Pat. Nos. 4,108,786; 4,256,818; 4,265,993; 4,543,312; 4,564,573; 4,600,676 and 4,777,104, which disclose colored toners and the use of, for example, cobalt as the magnetic ingredients, see for example column 3, beginning at line 44, of the '786 patent and note particularly column 3, at around line 53, wherein cobalt powder is disclosed as an inorganic magnetic material for the toner of the '786 patent, and also note that colored pigments such as yellow, orange, red, violet, blue, green, white and the like can be selected, see columns 4 and 5 of the aforementioned '786 patent, however, it appears that this patent is silent with respect to encapsulated toners and the use thereof in magnetic image character recognition processes; U.S. Pat. No. 4,517,268 mentioned herein; and as collateral interest U.S. Pat. Nos. 3,905,841; 4,284,700; 4,436,803 and 4,623,602. The disclosures of each of the aforementioned patents, particularly the '786, '818, '993, '312, '573, '676, '104 and '268 patents, are totally incorporated herein by reference.
Also, encapsulated and cold pressure fixable colored toner compositions are known. A number of the prior art cold pressure fixable colored toner compositions suffer from a number of deficiencies. For example, the prior art colored toners, particularly magnetic colored toners, usually do not possess sufficiently high magnetic remanance of, for example, 25 to 300 Gauss, together with high magnetic saturation moment of from about 90 to 150 emu/gram, and coercivity of from about 80 to about 800 Oersteds to be effectively useful for MICR applications. Documents generated by cold pressure fixable colored toner compositions of copending U.S. Ser. No. 546,278 (D/90069), the disclosure of which is totally incorporated herein by reference, can possess a high magnetic saturation moment, however, they lack the appropriate high remanance. The toners of the present invention are preferably useful for the generation of colored MICR documents, excluding black documents.
The following United States patents are mentioned: U.S. Pat. No. 4,803,144, which discloses an encapsulated toner with a core containing as a magnetizable substance, a magnetite, see Example 1, which is black in color; U.S. Pat. No. 4,734,350 which discloses an improved positively charged toner with modified charge additives comprised of flow aid compositions having chemically bonded thereto, or chemiadsorbed on the surface certain amino alcohol derivatives, see the Abstract for example; the disclosures of each of the aforementioned patents being totally incorporated herein by reference; and perhaps of some background interest U.S. Pat. Nos. 2,986,521; 4,051,077; 4,108,653; 4,301,228; 4,301,228 and 4,626,487.
In a patentability search report in a copending application U.S. Ser. No. 609,333 (D/90192), the disclosure of which is totally incorporated herein by reference, the following United States patents were listed: U.S. Pat. No. 4,514,484 directed to a powder suitable for developing latent images comprised of magnetic particles coated with a mixture of a thermoplastic resin and a silane, see for example the Abstract of the Disclosure; note column 3, beginning at line 15, wherein it is indicated that into the organic thermoplastic resin is incorporated a silane selected from those illustrated; U.S. Pat. Nos. 4,517,268 relating to xerographic toners for MICR printing; 4,268,598 which discloses a magnetic toner for the printing of machine readable legends; 4,748,506 relating to magnetic encapsulated toners, see column 4, wherein there is mentioned, for example, Columbia Mapico Black and Bayferrox magnetites; and 3,627,682; 4,439,510; 4,536,462 and 4,581,312, which patents disclose, for example, encapsulated toners with magnetites. The disclosures of each of the aforementioned patents are totally incorporated herein by reference.
Illustrated in copending application U.S. Ser. No. 609,316 (D/90192Q), the disclosure of which is totally incorporated herein by reference are a colored magnetic encapsulated toner composition comprised of a core comprised of a polymer binder, a colorless or light colored magnetic material, a color pigment, dye or mixture thereof excluding black, and a whitening agent, and which core is encapsulated in a polymeric shell containing therein or thereon a conductive metal oxide powder; a colored conductive magnetic encapsulated toner composition comprised of a core comprised of a polymer binder, a substantially colorless magnetic material, a color pigment, excluding black, and a whitening agent, and which core is encapsulated in a polymeric shell containing thereon a conductive metal oxide powder, and wherein the toner has a volume of from about 10.sup.3 ohm-cm to about 10.sup.8 ohm-cm; a colored magnetic encapsulated toner composition comprised of a core comprised of a polymer binder, a grayish color magnetic material, a pigment, and a whitening agent, and wherein the core is encapsulated in a polymeric shell containing a conductive metal oxide powder, and wherein the toner has a volume of from about 10.sup. 4 ohm-cm to about 10.sup.6 ohm-cm, which metal oxide can be comprised of the oxides of aluminum, antimony, barium, bismuth, cadmium, chromium, germanium, indium, lithium, magnesium, molybdenum, nickel, niobium, ruthenium, silicon, tantalum, titanium, tin, vanadium, zinc, zirconium, mixtures thereof and the like.
In copending application U.S. Ser. No. 445,221 (D/89086), the disclosure of which is totally incorporated herein by reference, there are illustrated magnetic image character recognition processes with encapsulated toners wherein there is selected as the magnetite a black magnetite such as MAPICO BLACK.TM.. More specifically, there is illustrated in this copending application an ionographic process which comprises the generation of a latent image comprised of characters; developing the image with an encapsulated magnetic toner comprised of a core comprised of a polymer and magnetitie with a coercivity of from about 80 to about 250 Oersteds, and a remanence of from about 20 to about 70 Gauss, and wherein the core is encapsulated within a polymeric shell; and subsequently providing the developed image with magnetic ink characters thereon to a reader/sorter device whereby toner offsetting and image smearing is minimized in said device.
There is a need for magnetic image character recognition (MICR) processes enabling the generation of documents, such as personal checks, with colored encapsulated toner and developer compositions wherein toner offsetting and image smearing is avoided, and the magnetic strength signal in an embodiment are from a desirable detection range of about 75 to about 150 percent on the ON-US character. There is also a need for the generation of developed images including the generation of personal checks in laser printers or ionographic printers utilizing magnetic ink character recognition technology, wherein image offset to protective foils present on the read and write heads is avoided or minimized, and image smearing is avoided or minimized. More specifically, there is a need for colored encapsulated toners wherein image ghosting is eliminated or minimized. In addition, there is a need for colored encapsulated toner processes for generating high quality MICR images whose magnetic integrity can be maintained after many passes in MICR reading and sorting processes. Also, there is a need for pressure fixable process toners which offer high quality images with fixing levels of, for example, over 70 percent at low fixing pressure, of for example, 2,000 psi.
The aforementioned needs and others can be accomplished by the provision of colored encapsulated toners of the present invention, preferably with a high, for example 40 to 75 weight percent of magnetic metal loadings, or lightly colored metal magnetites with magnetic saturation moments of from about 70 to 120 emu per gram and remanance of about 25 to 75 Gauss to provide the desired magnetic signal strength in the MICR reader.